Merge "Fix race condition in eventletutils Event"

lower-constraints.txt

@@ -4,6 +4,7 @@ bandit==1.4.0
 coverage==4.0
 ddt==1.0.1
 debtcollector==1.2.0
+eventlet==0.18.2
 extras==1.0.0
 fixtures==3.0.0
 flake8==2.5.5

oslo_utils/eventletutils.py

@@ -24,6 +24,8 @@ import threading
 import warnings
 
 from oslo_utils import importutils
+from oslo_utils import timeutils
+
 
 # These may or may not exist; so carefully import them if we can...
 _eventlet = importutils.try_import('eventlet')
@@ -151,8 +153,11 @@ class EventletEvent(object):
         self.clear()
 
     def clear(self):
+        old_event = getattr(self, "_event", None)
         self._set = False
         self._event = _eventlet.event.Event()
+        if old_event is not None:
+            old_event.send(True)
 
     def is_set(self):
         return self._set
@@ -167,9 +172,15 @@ class EventletEvent(object):
         self._event.send(True)
 
     def wait(self, timeout=None):
-        with _eventlet.timeout.Timeout(timeout, False):
-            self._event.wait()
-        return self.is_set()
+        with timeutils.StopWatch(timeout) as sw:
+            while True:
+                event = self._event
+                with _eventlet.timeout.Timeout(sw.leftover(return_none=True),
+                                               False):
+                    event.wait()
+                    if event is not self._event:
+                        continue
+                return self.is_set()
 
 
 def Event():

oslo_utils/tests/test_eventletutils.py

@@ -15,6 +15,8 @@
 import threading
 import warnings
 
+import eventlet
+from eventlet import greenthread
 import mock
 from oslotest import base as test_base
 import six
@@ -150,3 +152,52 @@ class EventletUtilsTest(test_base.BaseTestCase):
         self.assertEqual(0, mock_eventlet.event.Event().reset.call_count)
         e_event.set()
         self.assertEqual(1, mock_eventlet.event.Event().reset.call_count)
+
+    def test_event_no_timeout(self):
+        event = eventletutils.EventletEvent()
+
+        def thread_a():
+            self.assertTrue(event.wait())
+
+        a = greenthread.spawn(thread_a)
+
+        with eventlet.timeout.Timeout(0.5, False):
+            a.wait()
+            self.fail('wait() timed out')
+
+    def test_event_race(self):
+        event = eventletutils.EventletEvent()
+
+        def thread_a():
+            self.assertTrue(event.wait(2))
+
+        a = greenthread.spawn(thread_a)
+
+        def thread_b():
+            eventlet.sleep(0.1)
+            event.clear()
+            event.set()
+            a.wait()
+
+        b = greenthread.spawn(thread_b)
+        with eventlet.timeout.Timeout(0.5):
+            b.wait()
+
+    def test_event_clear_timeout(self):
+        event = eventletutils.EventletEvent()
+
+        def thread_a():
+            self.assertFalse(event.wait(0.5))
+
+        a = greenthread.spawn(thread_a)
+
+        def thread_b():
+            eventlet.sleep(0.1)
+            event.clear()
+            eventlet.sleep(0.1)
+            event.clear()
+            a.wait()
+
+        b = greenthread.spawn(thread_b)
+        with eventlet.timeout.Timeout(0.7):
+            b.wait()

test-requirements.txt

@@ -4,6 +4,7 @@
 
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 
+eventlet>=0.18.2,!=0.18.3,!=0.20.1,!=0.21.0,!=0.23.0 # MIT
 fixtures>=3.0.0 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT